This invention relates to a device for transferring bar-shaped articles.
The invention finds particularly advantageous application in the production of smoking articles, in particular cigarettes, to which the description given hereinafter makes specific reference but without thereby limiting its general application.
During cigarette production, it is sometimes necessary to cause the cigarettes to undergo a tranverse translational movement and a simultaneous rotary movement about their axis for specific process manipulation purposes.
To cause the cigarettes to undergo roto-translational motion, it is known to use a transfer device in which the cigarettes to be manipulated are transferred from an inlet roller to a transfer roller disposed tangential to said inlet roller and provided along its outer periphery with a plurality of rotatable cradles. Each cradle is arranged to house a respective cigarette and to surrender it, on completion of transfer, to an outlet roller tangential to said transfer roller.
As each cradle passes through the positions in which it is tangential to the inlet and outlet rollers, it lies in a determined angular rest position relative to the transfer roller in order to facilitate correct cigarette transfer between the inlet, transfer and outlet rollers. While it traverses a central portion of its path of advancement between the two said points of tangency, each cradle is rotated firstly at increasing angular speed, then at constant angular speed, and then at decreasing angular speed. Each cigarette is manipulated as it advances along a manipulation arc, along which the relative cradle rotates about its axis at the said constant angular speed. In the aforesaid known transfer device, the cigarettes are subjected to considerable positive and negative angular acceleration as they advance along the transfer roller, and this can compromise their structural stability, at least causing tobacco to escape. Moreover, as a result of the need to angularly accelerate and then decelerate said cradles, the width of the manipulation arc is relatively small.
Finally, from the mechanical aspect, the aforesaid known transfer device has a relatively complicated structure due to the need to vary the angular speed with which the cradles rotate about their axis between zero and a determined constant value during each complete revolution of the transfer roller about its axis.